1. Description of the Related Art
Conventional locking device with an electronic control generally adopts a locking assembly driven by a micro DC motor, and one of the technical solutions uses a coil spring sheathed on a shaft and a pin fixed to the shaft to convert a rotational motion of the motor into a linear motion between the spring and the pin, so as to push or pull a blocking element for controlling a lock bolt to retract.
As to the solution of using the rotation of the pin, when the pin moves spirally along the spring, the spring is compressed by the pressure of the pin, so that a larger friction is produced, and a rotational force of the spring and the shaft is produced by the friction, so that the spring may be rotated together with the shaft and jittered radially, and the spring cannot be displaced stably in the axial direction, and thus not just resulting the wear-out or damage between the spring and the sliding block only, but also failing to allow the pin to enter into the spiral track of the spring successfully. In addition, the friction between the pin and the spring may also wear out the pin and the spring. As disclosed in P.R.C. Pat. No. CN201110244325.0, a pin is rotated to push a pin to push the spring to displace axially, so as to push a blocking element to be stretched out or retracted. To overcome the unintentional rotation and jitter of the spring, a third winding of the spring is provided to absorb and buffer the vibrations and impacts of the pin exerted to the pin and produced when the motor is turned on and rotated, so as to prevent the spring from being twisted, deformed, or shaken.
Alternatively, the coil spring is fixed onto the drive shaft of the motor and rotated together with the motor, and the pin is fixed to an axially slidable blocking element in order to achieve the effect of pushing or pulling the blocking element into a locked position or an unlocked position. As disclosed in U.S. Pat. No. 5,628,216 issued to Schlage Lock Company, a locking device is installed to a door lock and comprises a motor, a gear set coupled to the motor, a guiding shaft coupled to the gear set, a coil spring fixed to a free end of a cylinder of the guiding shaft and partially stretched coaxially into a bushing of a plug, and a pin perpendicularly installed to the bushing of the plug while passing through two adjacent rounds of the spring of the bushing of the plug. The motor drives the coil spring to rotate, and the pin is rotated into the two adjacent rounds of the coil spring, so that the bushing of the plug slides along the axis of the motor shaft and between a locked position and an unlocked position to control locking and unlocking the door lock.
Another patent further discloses a locking device of a door lock, and the difference between this patent and the aforementioned patent resides on that the pin of this patent is installed to a frame of a protrusion formed at an end of a locking plate, and a coil spring is passed through from the interior of the frame, and the pin is inserted between two adjacent rounds of the spring, and the locking plate is shifted axially between the locked position and the unlocked position under the precession effect of the spring and the pin.
The technical solutions provided by the foregoing patented technology have the following advantages. Since the spring and the drive shaft are fixed, the inertia of the rotation is small, and there is no issue on the rotation and radial shaking of the spring. However, there is still an unsatisfactory result. For example, the load (including the bushing of the plug and the locking plate) has relatively larger volume and weight, so that when the spring is rotated into the pin, the spring is pulled and stretched, and the friction in contact with the pin is increased, and the spring and pin may be worn out or damaged easily.
In addition, some actuator assemblies require a spring with a fixed end and a non-fixed longer end, so that when a portion of the actuator assembly away from the drive shaft is rotated, there is no radial limitation, and a swinging deviated from the axis may be produced to cause vibrations of the spring.
Obviously, the technical solution of ‘converting the rotational motion of the motor into the linear motion between the coil spring and the pin for the interaction of the pin and coil in order to push or pull a blocking element for controlling a locking device’ requires further improvements.
2. Summary of the Invention
Therefore, it is a primary objective of the present invention to provide an actuator assembly for a locking device, and the actuator assembly is capable of preventing the vibration produced by the rotation of the spring and reducing the friction between the pin and the spring.
To achieve the aforementioned and other objectives, the present invention provides an actuator assembly for a locking device with electronic control, comprising: a motor, having a drive shaft installed to a motor shaft, and a coil spring installed to the drive shaft, characterized in that the actuator assembly further comprises: a follower shaft capable of displacing in an axial direction in the coil spring, and a pin installed onto the follower shaft and rotatable into the coil spring, and the follower shaft is extended into the coil spring and slidably fitted to the coil spring.
Wherein, the coil spring is a cylinder spring comprising a rotating-in portion and a buffering portion, and the pin displaces axially within a range of the rotating-in portion.
Wherein, the buffering portion has a plurality of tightly wound windings with a pitch equal to zero, and the rotating-in portion has a pitch greater than the diameter of the pin.
Wherein, the external diameter of the follower shaft and the internal diameter of the cylinder spring have a unilateral gap of 0.15 mm˜0.30 mm, and the rotating-in portion has a pitch equal to 1.1˜1.3 times of the diameter of the pin.
Wherein, the cylinder spring has a first fixing ring and a second fixing ring installed at two free ends of the cylinder spring respectively, a first U-shaped bend coupled to the first fixing ring, and a second U-shaped bend coupled to the second fixing ring; the drive shaft has a ring-shaped protruding strip formed thereon, and the ring-shaped protruding strip comprises a protruding strip head matched with the first U-shaped bend, and the first U-shaped bend is sheathed on the protruding strip head, and the first fixing ring is installed to the outer side of the ring-shaped protruding strip.
Wherein, the follower shaft has a cylindroid disposed at an end of the follower shaft and protruded out from the outer peripheral surface of the follower shaft.
Wherein, the drive shaft includes a first shaft shoulder and a second shaft shoulder, a fixing frame installed between the drive shaft and the motor housing, and the fixing frame includes two fixing rods fixed to the motor housing and a third U-shaped bend perpendicular to the fixing rod, and the third U-shaped bend is disposed between the first shaft shoulder and the second shaft shoulder for limiting the axial displacement of the drive shaft.
Wherein, the fixing frame is formed by bending a steel wire, and the third U-shaped bend has a diameter smaller than the first shaft shoulder and greater than the second shaft shoulder.
Wherein, the motor shaft is a flat shaft, and the drive shaft includes a flat shaft hole matched with the flat shaft.
Wherein, the follower shaft includes a pin hole, and the pin has a head disposed between two adjacent rounds of the coil spring and a tail fixed to the pin hole.
In summation, the present invention has the following advantageous effects:
1. Compared with the prior art, the follower shaft of the present invention effectively maintains a radial limitation of the cylinder spring to overcome the vibration of the spring occurred during the rotation of the cylinder spring and the axial displacement of the follower shaft.
2. The cylinder spring of the present invention has the structure of the buffering portion, and when the pin displaces axially with respect to the cylinder spring, the buffering portion is also pulled and stretched, so that the rotating-in portion of the spring is pulled and stretched and the compression is reduced to effectively reduce the friction between the pin and the spring, so as to minimize the wear-out and damage of components.
3. The actuator assembly for the locking device in accordance with the present invention has the features of small number of components, simple structure, and easy manufacture and installation.